DEXA Scanning or bone densitometry is a simple, painless procedure used to measure bone mineral density and accurately diagnose osteoporosis, the bone-thinning disease that mainly affects post-menopausal women. The test is performed by a radiologist or technologist and requires no injections, sedation, special diet or any other advance preparation. In most cases, it can be completed in 30 minutes or less.
DEXA stands for Dual-Energy X-ray Absorptiometry. During this quick procedure, the patient lies fully clothed on a padded table while the DEXA scanner beams low dose X-rays from two different sources towards the bone being examined (usually the lower spine or hip). Two energy peaks are captured—one absorbed mainly by soft tissue and the other by bone. The difference between the soft tissue amount and total is the bone mineral density. A computer is then used to analyze the resulting images and calculate bone density based on the amount of radiation absorbed by the bone (the denser the bone, the more radiation it absorbs).
In addition to diagnosing osteoporosis, DEXA scanning can be used to measure and monitor a patient's response to treatment.
DEXA scanning advantages
DEXA scanning has become the most popular osteoporosis screener for several reasons, including:
- Accuracy – DEXA scanning uses two different X-ray energy sources, which helps make it the most sensitive, precise, and accurate method available to measure subtle changes in bone density over time or in response to drug therapy.
- Low radiation exposure – EXA scanning uses less radiation than other tests, such as CT scans or radiographic absorptiometry. In fact, DEXA scanning exposes patients to less radiation than a chest X-ray or a coast-to-coast airline flight.
- Versatility – Unlike other osteoporosis screeners, DEXA scanning can be used to test bone density in the entire body, including the spine and extremities.
- Cost – DEXA scanning is less expensive than other bone mineral density tests and thus more widely available to patients.
Who shouldn't use DEXA scanning?
Although DEXA scanning is the best method for measuring bone density, certain conditions may interfere with the accuracy of test. Those conditions include:
- Spinal deformities or previous spinal surgery
- Vertebral compression fractures or degenerative diseases such as osteoarthritis
- Calcium in the blood vessels that overlie the area being scanned (this condition, sometimes found in patients with heart disease, may falsely increase bone density)
- In addition, pregnant women should not undergo X-ray tests because exposure to ionizing radiation may harm the fetus.
What happens next?
An experienced Main Line Health radiologist will analyze your DEXA scans and send a report to your referring physician, who will inform you on your test results. Results cannot be given directly to the patient or family.